Synthesis of keto- and hydroxydienoic compounds from linoleic acid

Abstract A convenient preparative method has been developed for the synthesis of hydroxydienoic (9-HODE and 13-HODE) and ketodienoic compounds (9-KODE and 13-KODE) from natural linoleic acid. Methyl linoleate was treated with 1.25 eq. of m -chloroperbenzoic acid in alcoholic solution, giving a mixture of mono-epoxides (yield 60%), that was treated with a solution of HBr in MeOH to yield a mixture of the bromohydrins (yield 92%). The last was oxidized by Jones reagent to a mixture of bromoketones (yield 64%) and the mixture obtained was dehydrobrominated by DBU to produce a mixture of ketodienoic compounds (yield 94%). Reduction of the ketodienoic compounds by KBH 4 in MeOH led to the corresponding hydroxydienoic (9-HODE and 13-HODE) methyl esters (yield 83%). The synthetic approach described is simple and gives reliable results. The keto- and hydroxy fatty acids obtained were characterized thoroughly by TLC, HPLC, UV, FT-IR, 1 H-, 1 H 1 H- and 13 C-NMR.